To measure conditions of a high-temperature and high-pressure molten liquid in an injection molding device, non-contact measurement is usually conducted by using an ultrasonic sensor. To protect the ultrasonic sensor, an additional fixing element is usually used to mount the ultrasonic sensor at an outer periphery of the injection molding device to further perform the measurement.
However, when performing measurement by the above means, separation caused by numerous interfaces exist between the ultrasonic sensor and the molten liquid. That is to say, ultrasonic signals transmitted from the ultrasonic sensor need to pass through numerous interfaces such as the additional fixing element and the injection molding device before they can arrive at the molten liquid, and then become reflected by the molten liquid, resulting in indirect effects upon the detection mechanism. In other words, the ultrasonic signals, after passing through many indirect interfaces, form a non-direct wave interface, which not only reduces the signal strength and generates signal interference but also easily and directly affects an outcome of signal parsing. As a result, additional signal processing may be needed, causing tedious and time-consuming technical actions.